A Simple Confocal Microscopy-based Method for Assessing Sperm Movement

In the field of reproductive medicine, assessment of sperm motility is a key factor for achieving successful artificial insemination, in vitro fertilization, or intracellular sperm injection. In this study, the motility of boar sperms was estimated using real-time imaging via confocal microscopy. To confirm this confocal imaging method, flagellar beats and whiplash-like movement angles were compared between fresh and low-temperature-preserved ($17^{\circ}C$ for 24 h) porcine sperms. Low-temperature preservation reduced the number of flagellar beats from $11.0{\pm}2.3beats/s$ (fresh sperm) to $5.7{\pm}1.8beats/s$ and increased the flagellar bending angle from $19.8^{\circ}{\pm}13.8^{\circ}$ (fresh) to $30.6^{\circ}{\pm}15.6^{\circ}$. These data suggest that sperm activity can be assessed using confocal microscopy. The observed motility patterns could be used to develop a sperm evaluation index and automated confocal microscopic sperm motility analysis techniques.